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whats in your water?

Just wanted to share an article I got in my water bill a couple of months ago. In order to understand your pool completely you must understand what happens to the water before you fill it up. I am curious what the gurus here think about this. Obviously this would be different based on where you live even the street you live on. It was taken from Gwinnett County Water Words.

The Water Treatment Process
Because of the excellent water quality of water from Lake Lanier, Gwinnett is able to utilize what is known as a direct filtration process for purification. Incoming water is first disinfected with ozone, an extremely powerful oxidant that kills bacteria, inactivates viruses and protozoans, and oxidizes naturally occuring organic compounds found in surface waters. Following ozonation, two chemicals known as coagulants are added to facilitate removal of suspended matter from the water. These chemicals are ferric chlroide and a liquid cationic polymer. Immediately after addition of these chemicals a short (one minute), intense mixing process takes place, followed by a slower more gentle mix period of 15 minutes. This process is called flocculation. After flocculation, water moves to the filtration step. Filters consist of fourt feet of anthracite, sitting on top of one foot of sand. The filter media (the sand and anthracite) is made up of very specific sized grains to achieve maximum removal of suspended material. After filtration, water receives its final chemical application on its way to on-site storage, until it is pumped into the water distribution system.

Gwinnett uses chlorine as the final disinfectant. State and federal safe drinking act regulations require that a disinfectant residual be maintaind throughout the water distribution system. Typical chlorine residuals are 1.8-2.0 mg/l leaving the water treatment plant. Residuals gradually decrease through the distribution system. Georgia law requires fluoridation of drinking water to prevent dental caries in children. Naturally occuring fluoride in waters in this part of the state are .3-.4 mg/l. Enough fluoride is added at the water treatment plant to bring the fluoride level to .8 mg/l a concentration recommended by the american dental association. Water from lake lanier is very "soft", meaning that it has low levels of dissolved minerals. Soft water is also very corrosive, and steps are taken to reduce this corrosivity, using a phosphate-based corrosion inhibitor. The corrosion inhibitor (an ortho/polyphosphate blend) minimizes corrosion of metal pipes and plumbing fixtures. Corrosion inhibitors are most effective in a ph range of 7.2-7.5 units. Water from lake lanier is usually slightly acidic with a ph of about 6.8. Finished water ph is adjusted to 7.2 units (just slightly basic) with a liquid lime ( calcium hydroxide) product.

The Combined Chlorine (CC) is due to my water system using monochloramine as the residual disinfectant instead of chlorine. Many water systems are switching over to avoid disinfection by-products (DPBs) from chlorine and to ensure that the residual lasts longer. One nice side effect of this is that it lets me test whether our under-the-sink water filter is working properly since it produces 0 CC (and 0 FC) when it is in good shape.

The water report only reports Total Hardness, not Calcium Hardness, but I was able to roughly calculate that based on typical calcium to magnesium ratios in our area's water.

Well water is typically far higher in TA, CH or both. The water from our water system is a mix of 75% runoff reservoir with 25% river water (and some groundwater wells).

All other contaminants are at miniscule levels. The only items of significance (other than the above) are copper at 0.1 ppm, chloride at around 20 ppm, sulfate at 9 ppm, TDS at 130 ppm, zinc at 0.4 ppm, and sodium at 18 ppm.